Weight regulator for a chair

ABSTRACT

A method of regulating the weight of a chair comprising a base frame ( 2 ) to support a seat face as well as a spring system ( 3 ) having adjustment means ( 20, 21 ), wherein the resilience of the chair is adjusted by unloaded adjustment means, and the adjustment is performed by moving one or more of the adjustment means ( 20, 21 ) at a time along a portion of the circumference of the base frame ( 2 ), and wherein the adjustment means adjusted first performs a coarse adjustment, following which a fine adjustment is performed with a second adjustment means. The invention also relates to a weight regulator for a chair, said chair comprising adjustment means for individual adjustment of the resilience of the seat and/or the backrest of the chair in dependence on the user&#39;s weight, said weight regulator comprising primary adjustment means for a coarse adjustment and secondary adjustment means for a fine adjustment of the resilience of the seat or of the backrest by tilting/movement, said adjustment means ( 20, 21 ) operating between a lower bearing point ( 19 ) and a base frame ( 2 ), said adjustment means ( 20, 21 ) being unloaded at the moment of adjustment.

The invention relates to a method of regulating the weight of a chair comprising a base frame to support a seat face as well as a spring system having adjustment means for adjusting the resilience of a weight regulator in dependence on the user's weight.

The invention also relates to a weight regulator for a chair comprising a base frame to support a seat face as well as a spring system having adjustment means for adjusting the resilience of the weight regulator in dependence on the user's weight.

PRIOR ART

In connection with sedentary work environments, e.g. office environments, involving frequent changes between various working postures, it is known to produce chairs comprising a weight regulator which causes the seat and the backrest to follow the user's movements in relation to the given working posture by virtue of the user's weight.

Such a chair is known e.g. from U.S. Pat. No. 5,397,165, where the weight regulator comprises a spring system which permits the user to tighten or relax the spring tension by means of a screw device and thereby to adjust the tilt function of the weight regulator, that is the resilience of the chair to the user's weight.

However, the weight regulator and thereby the resilience of the chair cannot be adjusted in relation to the user's weight. Hereby, a very light person will not have the same benefit from the weight regulator of the chair as a heavier person, just as it is not possible to satisfy the individual ergonomic wishes which the user might have in respect of a such a weight regulating chair.

Further, it is known from DE 4 231 057 to have a form of forced control between the inclination of the seat and the position of the backrest, where the inclination of the seat depends on the users weight. When, thus, the user leans forwards on the chair, the weight of the user will be concentrated on the front part of the seat and will cause the seat face to tilt from a neutral position (horizontal) and forwards, while the plane of contact of the backrest relative to the user moves closer to the vertical axis of rotation of the chair. Correspondingly, when the user leans back in the chair and thereby applies a pressure to the backrest, the seat will be tilted back. The resistance of the screw device increases in proportion to the tension of the spring, which frequently means that the user has to get up from the chair when the spring is to be tightened. Therefore, the user must alternatively sit and stand until the resilience of the chair correct for the user has been set, which is time-consuming per se.

A serious drawback of the weight regulation in both U.S. Pat. No. 5,397,165 and in DE 4 231 057 is that the regulating principle is operated by a screw device, where the user often has to screw so long that this creates doubts of the effect of the function which the user wishes to affect. Therefore, the result is frequently that the user refrains from using the adjustment option, and, consequently, the ergonomic advantages which the product has been manufactured to offer, are not utilized. Thereby, the user has no optimum use and optimum comfort of the chair, just as the intended support for minimum loading of the body in a sitting posture is not achieved.

The Novel Art

The invention is intended to provide a weight regulator where the user's weight on the backrest of the chair means that the resilience individually satisfies the user's ergonomic wishes irrespective of the user's weight and various working postures.

The weight regulator will thus be instrumental in allowing the chair to be adjusted easily and without the use of tools, whereby the user will be motivated to adjust the chair correctly. Thus, in case of various users, the maximum comfort of the chair can be utilized each time.

This is achieved according to the method in that the resilience of the chair is adjusted by unloaded adjustment means, and that the adjustment is performed by moving one or more of the adjustment means at a time along a portion of the circumference of the base frame.

The adjustment described in claim 2 ensures that the resilience of the weight regulator may be adjusted very accurately in a simple and easy manner, such that it is adapted to the instantaneous user who uses the chair.

This is possible with a chair according to the invention in that the weight regulator comprises primary adjustment means for a coarse adjustment and secondary adjustment means for a fine adjustment of the resilience of the backrest and partially the seat by tilting/movement, said adjustment means operating between a lower bearing point and a base frame, and that the adjustment means are unloaded at the moment of adjustment.

Claims 3 to 5 provide an easy way of performing a very accurate adjustment of the resilience of the weight regulator according to the user who is to use the chair.

The invention, as described in claims 6 to 8, provides a releasable retention of the end part of the adjustment means in a given position relative to the base frame, so that the position suitable for the user may be maintained.

Claim 9 describes means of adjusting the sitting length of the seat, which is important inter alia for the support of the user's thighs.

Claim 10 describes an embodiment of the base frame with the option of arranging a backrest which moves together with the base frame.

The invention will be described more fully below with reference to the drawing, in which

FIG. 1 shows a weight regulator according to the invention for a chair, seen in perspective,

FIG. 2 shows the weight regulator shown in FIG. 1, seen from above,

FIG. 3 shows the weight regulator shown in FIG. 1, seen in a position from behind, and

FIG. 4 shows the weight regulator shown in FIG. 1, seen from the side.

EXEMPLARY EMBODIMENT

FIGS. 1 and 2 show a preferred embodiment of a weight regulator 1 according to the invention for a chair, said weight regulator 1 essentially consisting of a base frame 2 and a spring system 3 mounted on the base frame 2. In the exemplary embodiment shown, the base frame 2 is configured as a circular ring having an essentially circular cross-section, but another configuration and/or cross-section is possible.

In a portion along the circular ring, the base frame 2 is enclosed by the shortest one end member of an essentially rectangular bracket 4, whose other end member is oriented inwards toward the interior of the base frame 2. The bracket 4 comprises a through recess 6 on its upper face 5. As will appear from FIG. 2, the recess 6 is arranged centrally on the upper face 5 measured between the two side faces 9, 9 of the bracket and extends from the other end member of the bracket 4, which is oriented toward the interior of the base frame 2, toward, but not to, the centre of the bracket 4, measured between the one end member and the other end member, respectively.

The line which may be formed on the basis of and measured centrally between the lateral boundaries 10 of the recess 6, constitutes the centre line C of the weight regulator 1. Two bores 11 for securing the backrest of the chair (not shown in the drawing) are arranged symmetrically on both sides of and at a certain distance from the intersection of the centre line C with the base frame 2. The number of bores 11 is not limited to two and may thus be one or more. If the number of bores 11 is one, it will preferably be positioned centrally relative to the centre line C or in the immediate vicinity thereof.

A plurality of depressions 12 are provided in the lower and inner periphery of the base frame 1 on the side of each bore 11 which forms the shortest circular arc to the bracket 4. The depressions 12 are positioned with a mutual spacing, and, as will appear from FIG. 2, the depressions 12 substantially extend in a circular arc to an angle which corresponds to essentially 90° relative to the centre axis C. The spacing between the depressions 12 may be the same and/or different on the same side as well as on each side of the centre axis C. The function of the depressions 12 will be described more fully below.

As will additionally appear from FIGS. 1 and 2, a plate 13 is positioned in extension of the recess 6 of the bracket, said plate having a rubber block 7, on which the seat face rests, at the end most remote from the recess 6 itself.

In connection with the one end member of the bracket 4 where this encloses the base frame 2, a recess 8 is provided in each of the side faces 9 of the bracket, and a bearing 14 is provided in each recess 8, where a part of each bearing 14 covers the base frame 2. A plate 15 engaging the recess 8 (see FIG. 2) is provided in extension of each bearing 14. Owing to the recesses 8, the bracket 4 is capable of sliding to and fro, which allows the depth of the seat face to be adjusted to the individual user's build. Thus, when the seat face rests on the rubber block 7, the depth of the seat face will be maintained in its adjusted position because of the user's weight and the friction between the seat face and the rubber block 7 created thereby.

It appears from the foregoing that the recesses 8 are provided as two separate recesses 8. This is just to be considered as a single exemplary embodiment, as the recesses 8 may very well be replaced by a single through-going recess. Nor is the shape of the recesses 8 of importance; it is just important that the depth of the seat face may be adjusted.

As will appear from FIGS. 3 and 4, an opening 17 is arranged on the lower face 16 of the bracket 4 for the carrying column (not shown in the drawing) of the chair. It will be seen from FIG. 4 that the opening 17 is arranged such that the centre line of the opening 17 essentially intersects the transverse centre line of the bearing 14. Thus, a “common point” will be provided from where the bracket 4 may move relative to the base frame 2. This “common point”, however, is not a structural requirement, but will result in a compact structure which does not take up unnecessary space.

In connection with the cooperation between the plates 15 and respective recesses 8, a U-shaped strap 18 is mounted on the lower face 16 of the bracket 4, said strap extending from one recess 8 down below the bracket 4 to the other recess 8. A rotatable bearing 19, to which two legs 20 in the form of gas dampers are secured, is mounted in the lower point of symmetry S of the U-shaped strap. Mechanical springs, gas springs, rubber or another resilient material, however, may also be used. A ball head 21 enclosing the base frame 2 is mounted at the other end of the legs 20.

Each of the ball heads 21 comprises a pawl or the like (not shown in the drawing) for engagement with respective depressions 12 of the base frame 2 on each side of the bores 11 to the front edge of the seat face. The engagement of the ball heads 21 with the depressions 12 may be regulated/adjusted by means of incorporated pressure devices or by simple spring action via a pawl, ball or the like (not shown in the drawing). The ball heads 21 may have other shapes, but the rounded shape is most expedient, as, thus, there will no sharp corners or edges. The ball heads 21 with associated legs 20 will be called a spring system 3 below, which is thus characterized in that one end may be moved in a circular arc, while the other forms a centre.

An essential feature of the invention is that the spring system 3 consists of two essentially stepless adjustment options for the resilience, viz. a coarse adjustment and a fine adjustment. Thus, the user performs a coarse adjustment with the one ball head 21 and a fine adjustment with the other ball head 21.

The spring system 3 will take on a different resistance owing to its circular movement, and with reference to FIG. 2, the spring system 3 will take on a maximum resistance in the outer position A and drop to a minimum in the other outer position B in step with the increase or reduction of the moment arm on the legs 20, which applies to both adjustment options.

The coarse and fine adjustments may be performed from the side desired by the user, as the coarse adjustment is performed by the ball head 21 which is adjusted first, whereby the other ball head 21 is thus used for the optional subsequent fine adjustment.

The resistance in the outer positions A and B may be selected in relation to the use of the spring system 3, that it is the field of use of the chair. In this exemplary embodiment, the resistance in the outer positions A and B are adapted to the use of the chair as an office chair, that is on the basis of a personal weight in the range of about 50-120 kg.

The principle of the weight regulator 1 described above is thus that the spring system 3 at one end may move in a circular arc with a varying resistance, while the other end forms a centre, whereby the chair may be adjusted to the resilience which the individual user might wish. In this exemplary embodiment, the spring system 3 consists of ball heads 21 with associated legs 20, where the ball heads 21 with a pawl or the like enclose the base frame 2 and thus perform either the coarse adjustment or the fine adjustment (resilience).

The very structure of the mechanism performing the coarse and fine adjustments, in this exemplary embodiment ball heads 21 with a pawl for engagement with the depressions 12 of the base frame 2, shall not be considered as a limited embodiment, as other configurations of the mechanism are possible. For example, the base frame 2 may be made without depressions 12, where e.g. the pawl in each ball head 21 is replaced by a spring device (not shown in the drawing) which is capable of applying the necessary pressure to the base frame 2 at coarse and fine adjustments.

With the preferred embodiment of the invention, the base frame 2 of the chair and thereby the seat face (not shown in the drawing) will assume an essentially horizontal position in the unloaded state of the chair, that is when the chair is not affected by any weight. This is illustrated in FIGS. 1-4.

When a user sits on the chair, the base frame 2 will be subjected to a weight load, as the user affects the backrest, which will cause compression of the spring system 3 and the base frame 2, and the seat face will likewise assume a less rearward inclination. The exact inclination of the base frame 2 or the seat face will depend solely on the user's weight.

If the user leans forwards, the weight impact will be stronger on the front of the base frame 2 and the base frame 2, because the load on the backrest is reduced, and thereby the backrest and partly the seat face will follow the user and the inclination will be smaller.

If the user should want a specific inclination or resilience, the user adjusts it by coarse and fine adjustments of the ball heads 21. Based on the stated neutral position of the ball heads 21, the resilience may thus be adjusted by changing the positions of the ball heads 21 toward the outer positions A and B. If less resilience is desired, the one ball head 21 is coarsely adjusted toward the outer position A, and if a corresponding greater resilience is desired, a coarse adjustment toward the outer position B is performed.

Subsequently, a fine adjustment may be performed with the other ball head 21, if the desired resilience is present between two points on the coarse adjustment. The fine adjustment is performed according to the same principle as the coarse adjustment, that is the other ball head 21 is rotated toward either the outer position A or B.

The adjusted resilience of the chair will be maintained when a given user gets up from the chair, just as the base frame 2 of the chair with backrest will return to the neutral starting position. 

1. A method of regulating the weight of a chair comprising a base frame to support a seat face as well as a spring system having adjustment means, characterized in that the resilience of the chair is adjusted by unloaded adjustment means, and that the adjustment is performed by moving one or more of the adjustment means at a time along a portion of the circumference of the base frame.
 2. A method according to claim 1, characterized in that the adjustment means adjusted first performs a coarse adjustment, following which a fine adjustment is performed with a second adjustment means.
 3. A weight regulator for a chair, said chair comprising adjustment means for individual adjustment of the resilience of a backrest of the chair in dependence on the user's weight, characterized in that the weight regulator comprises primary adjustment means for a coarse adjustment and second adjustment means for a fine adjustment of the resilience of the backrest by tilting/movement, said adjustment means operating between a lower bearing point and a base frame, and that the adjustment means are unloaded at the moment of adjustment.
 4. A weight regulator according to claim 3, characterized in that the adjustment means are formed by spring elements which are rotatably secured at one end at a bearing point and is provided with an end part at the other end, said end part enclosing a portion of an essentially ring-shaped base frame.
 5. A weight regulator according to claim 3, characterized in that the base frame is arranged tiltably around an essentially horizontal axis extending through a bracket such that the base frame is capable of tilting around the part of the base frame which faces forwards in the sitting direction of the chair.
 6. A weight regulator according to claim 4, characterized in that the end part of the adjustment means comprises holding means for holding the end part in a given position relative to the base frame.
 7. A weight regulator according to claim 6, characterized in that the end part of the adjustment means accommodates a form of slide bushing which, when affected by the user, may be brought to a released state such that the slide bushing may be moved freely along the curve of the base frame, and to a secured state when there is no action from the user such that the friction increases sufficiently to hold the end part in a given position relative to the base frame.
 8. A weight regulator according to claim 7, characterized in that blocking means are arranged at the end part of the adjustment means, said blocking means being intended to engage corresponding depressions and/or elevations in the base frame for holding the end part in a given position relative to the base frame.
 9. A weight regulator according to claim 5, characterized in that the bracket is provided with one or more pairs of recesses in which the base frame may be displaced for adjusting the depth of the seat face.
 10. A weight regulator according to claim 3, characterized in that at the part facing rearwards in the sitting direction, the base frame is provided with one or more holes for the application of a backrest. 